1. Technical Field
The present invention relates to a fuel injection apparatus which increases a pressure of a fuel within a fuel source by a fuel pump so as to supply the fuel into the fuel distribution path of a fuel distribution pipe and injects and supplies a fuel controlled by a fuel injection valve mounted to the fuel distribution pipe toward an engine, and more particularly to a fuel distribution pipe provided with a fuel distribution path.
2. Description of the Prior Art
A fuel distribution path is pierced in a fuel distribution pipe in a longitudinal axial direction.
A fuel introduction path is connected and opened to the fuel distribution path, an injection valve supporting hole is opened to the fuel distribution path, a pressure of a fuel within a fuel source is increased and the fuel is supplied to the fuel introduction path by a fuel pump, and a rear end portion of a fuel injection valve for injecting and supplying the fuel is pressed into and supported to the injection valve supporting hole. Accordingly, the pressure of the fuel within the fuel source is increased by the fuel pump, and the fuel having the increased pressure is supplied into the fuel distribution path of the fuel distribution pipe via the fuel introduction path.
On the other hand, the fuel injection valve is structured such as to perform a fuel injection on the basis of an injection signal output from an electronic control unit (ECU), and the fuel having the increased pressure within the fuel distribution path is injected to an engine or an intake pipe or the like connected to the engine via the fuel injection valve.
In accordance with the conventional fuel injection apparatus mentioned above, a temperature of the fuel within the fuel distribution path of the fuel distribution pipe tends to be increased, and this is caused by the following reasons.
Firstly, it is because the fuel introduction path connecting the fuel pump to the fuel distribution path is heated and the fuel having an increased temperature is easily supplied into the fuel distribution path.
That is, the fuel introduction path is structured such as to be piped around within an engine room in which an atmospheric temperature is largely increased, whereby the fuel introduction path is heated by a heat within the engine room and the fuel flowing therein is heated so as to increase the temperature thereof.
Secondly, it is because the fuel distribution pipe is directly heated.
That is, the fuel distribution pipe is structured such as to be disposed within the engine room and arranged significantly near the engine, whereby the temperature is easily increased particularly due to an influence of heat generated at a time of operating the engine, so that the fuel within the fuel distribution pipe is directly heated.
Accordingly, when the temperature of the fuel within the fuel distribution path of the fuel distribution pipe is increased due to the causes mentioned above, vapors are generated in the fuel flowing within the fuel distribution path, so that when the vapors are supplied to the engine in a state of being contained in the fuel injected from the fuel injection valve, there is a risk of damaging a good operation property of the engine.
That is, when the fuel containing the vapors is supplied, the fuel is intermittently supplied and the fuel can not be continuously and stably supplied. Further, since an amount of fuel actually supplied is reduced in correspondence to an amount of the vapors, it is impossible to stably and accurately supply the fuel.
The present invention is made by taking the problems mentioned above into consideration, and a first object of the present invention is to provide a fuel distribution pipe which can restrict an increase of temperature of a fuel flowing within a fuel distribution path of a fuel distribution pipe so as to continuously supply the fuel stably and accurately to an engine, whereby it is possible to improve an operation property of the engine.
Further, a second object of the present invention is to prevent a sound caused by a pressure change of a fuel within a fuel distribution path generated by an opening and closing operation of a fuel injection valve from being transmitted to the outside.
In order to achieve the objects mentioned above, in accordance with a first aspect of the present invention, there is provided a fuel distribution pipe in a fuel injection apparatus structured such as to increase a pressure of a fuel within a fuel source by a fuel pump so as to supply to the fuel distribution pipe and inject and supply the fuel to an engine via a fuel injection valve attached to the fuel distribution pipe, in which the fuel distribution path is pierced along a line Xxe2x80x94X in a direction of a longitudinal of the fuel distribution pipe and an injection valve supporting hole for inserting and supporting a rear end portion of the fuel injection valve and a fuel introduction path for supplying a fuel having a pressure increased by a fuel pump are continuously provided in the fuel distribution path of the fuel distribution pipe, and in which a cooling water flow path extending along the line Xxe2x80x94X in the direction of the longitudinal axis of the fuel distribution path and sectioned from the fuel distribution path is provided on an outer periphery of the fuel distribution path, thereby introducing a cooling water into the cooling water flow path.
Further, in accordance with a second aspect of the present invention, there is provided a fuel distribution pipe in a fuel injection apparatus as recited in the first aspect, wherein a cooling water introduction path and a cooling water discharge path are opened to the cooling water flow path, thereby circulating the cooling water within the cooling water flow path.
Further, in accordance with a third aspect of the present invention, there is provided a fuel distribution pipe in a fuel injection apparatus as recited in the first aspect, wherein the fuel distribution path and the cooling water flow path are formed within the fuel distribution pipe in a sectional manner by forming the fuel distribution path and the cooling water flow path formed in the fuel distribution pipe so as to be opened in one end portion by a casting process, and closing the one end portion by one side closing member, and the fuel introduction path connected to the fuel distribution path and a cooling water introduction path connected to the cooling water flow path are provided in the one side closing member.
Further, in accordance with a fourth aspect of the present invention, there is provided a fuel distribution pipe in a fuel injection apparatus as recited in the third aspect, wherein the fuel introduction path connected to the fuel distribution path, the cooling water introduction path connected to the cooling water flow path and a cooling water discharge path are provided in the one side closing member.
Further, in accordance with a fifth aspect of the present invention, there is provided a fuel distribution pipe in a fuel injection apparatus as recited in the first aspect, wherein the fuel distribution path disposed along the line Xxe2x80x94X in the direction of the longitudinal axis within the fuel distribution pipe is formed so as to be sectioned from the cooling water flow path by forming the fuel distribution path and the cooling water flow path in the fuel distribution pipe by a drawing process along the line Xxe2x80x94X in the direction of the longitudinal axis and closing the fuel distribution path and the cooling water flow path respectively open to one end portion and another end portion of the fuel distribution pipe by one side closing member and another side closing member.
Further, in accordance with a sixth aspect of the present invention, there is provided a fuel distribution pipe in a fuel injection apparatus as recited in the fifth aspect, wherein the fuel introduction path connected to the fuel distribution path and the cooling water introduction path connected to the cooling water flow path are provided in the one side closing member.
Further, in accordance with a seventh aspect of the present invention, there is provided a fuel distribution pipe in a fuel injection apparatus as recited in the fifth aspect, wherein the fuel introduction path connected to the fuel distribution path and the cooling water introduction path and the cooling water discharge path connected to the cooling water flow path are provided in the one side closing member.
Further, in accordance with an eighth aspect of the present invention, there is provided a fuel distribution pipe in a fuel injection apparatus as recited in the fifth aspect, wherein the fuel introduction path connected to the fuel distribution path and the cooling water introduction path connected to the cooling water flow path are provided in the one side closing member, and the cooling water discharge path connected to the cooling water flow path is provided in the another side closing member.
Further, in accordance with a ninth aspect of the present invention, there is provided a fuel distribution pipe in a fuel injection apparatus as recited in the first aspect, wherein heat radiating fins disposed along the line Xxe2x80x94X in the direction of the longitudinal axis of the fuel distribution pipe are provided in any one or both of an outer peripheral wall of the fuel distribution path and an inner peripheral wall of the cooling water flow path.
Further, in accordance with a tenth aspect of the present invention, there is provided a fuel distribution pipe in a fuel injection apparatus as recited in the first aspect, wherein the cooling water flow path is sectioned into a first cooling water flow path and a second cooling water flow path along the line Xxe2x80x94X in the direction of the longitudinal axis by a partition wall, the first cooling water flow path and the second cooling water flow path are communicated by another end portion of the fuel distribution pipe, the cooling water introduction path is opened to the first cooling water flow path open to the one end portion, and the cooling water discharge path is opened to the second cooling water flow path open to the one end portion.
In accordance with the first aspect mentioned above, the fuel within the fuel distribution path of the fuel distribution pipe is cooled by the cooling water within the cooling water flow path provided in the outer periphery of the fuel distribution path, and when the heat within the engine room is applied to the fuel distribution pipe, the heat is cooled by the cooling water within the cooling water flow path so as to be prevented from being transmitted, thereby preventing the temperature of the fuel flowing within the fuel distribution path from being increased.
In accordance with the second aspect, since the cooling water within the cooling water flow path flows into from the cooling water introduction path and is discharged from the cooling water discharge path after flowing within the cooling water flow path so as to circulate within the cooling water flow path, it is possible to increase a cooling effect of the fuel within the fuel distribution path.
In accordance with the third aspect, the fuel distribution pipe is formed by a casting process, the opening of the one end portion of the fuel distribution pipe is closed by the one side closing member, and the inner portion of the fuel distribution pipe is sectioned into the fuel distribution path and the cooling water flow path. Further, since the fuel introduction path and the cooling water introduction path are provided in the one side closing member, it is possible to easily form the flow paths.
In accordance with the fourth aspect, since the fuel introduction path, the cooling water introduction path and the cooling water discharge path are provided in the one side closing member, it is possible to circulate the cooling water within the cooling water flow path by a simple structure, and it is possible to increase a cooling effect.
In accordance with the fifth aspect, the fuel distribution pipe is formed of the drawn material and the openings at both ends thereof are closed by the one side closing member and the another side closing member, thereby forming the fuel distribution pipe provided with the fuel distribution path and the cooling water flow path sectioned from each other, so that it is possible to reduce the manufacturing cost.
In accordance with the sixth aspect, since the fuel introduction path and the cooling water introduction path are provided in the one side closing member in the fuel distribution pipe made of the drawn material, it is possible to easily form the flow paths.
In accordance with the seventh aspect, since the fuel introduction path, the cooling water introduction path and the cooling water discharge path are provided in the one side closing member in the fuel distribution pipe made of the drawn material, it is possible to circulate the cooling water within the cooling water flow path in accordance with a simple structure, and it is possible to increase a cooling effect.
In accordance with the eighth aspect, in the fuel distribution pipe made of the drawn material, since the fuel introduction path and the cooling water introduction path are provided in the one side closing member and the cooling water discharge path is provided in the another side closing member, it is possible to securely circulate the cooling water within the cooling water path, so that it is possible to further improve a cooling property of the fuel within the fuel distribution path.
In accordance with the ninth aspect, since the heat radiating area is increased by the heat radiating fin, it is possible to increase a heat radiating property with respect to the cooling water and it is possible to further effectively restrict an increase of temperature of the fuel flowing within the fuel distribution path.
In accordance with the tenth aspect, the cooling water path is sectioned into the first cooling water path and the second cooling water path by the partition wall, and the paths are connected at the another end and are respectively sectioned at the one end and opened.
Since the cooling water flows downstream through the first cooling water path and thereafter U-turns toward and flows through the second cooling water path, it is possible to largely improve the cooling effect of the fuel within the fuel distribution path. Further, it is possible to improve a rigidity of the fuel distribution pipe by the partition wall.